Kansas City Industrial Council Hydrology and Hydraulics Chance J. Bitner, PE Chief, Hydrology and Hydraulics Section Kansas City District 30 June 2015

Which river is the “toughest”? The Kansas River peaked at Desoto on May 8 at 120,000 cfs. In case asked, the 2011 flood peak was 32.6 ft at KC gage on the Missouri. May 8, 2007 – 4 hours before the peak; 286,000 cfs, 120,000 cfs peak flow on the Kansas River at Desoto

Overview Basic H&H FEMA Floodplain Climate Change

Overview Basic H&H FEMA Floodplain Climate Change Not to scale

Basic H&H Questions Hydrology How much water is coming? How often does that much flooding occur? How would it change if we build a reservoir? How much time before the flooding starts? Hydraulics How high is the water going to get? How fast is the water? Will that cause erosion? What areas are prone to flooding? How would the flow change if a levee is built?

Peaks at Kansas City ~705 kcfs w/out dams in place ~320 kcfs w/ today’s Dams in place 541 kcfs 573kcfs 286kcfs

1993 Flood w/out Dams USGS post 1993 report

Hydrology Basic Options Flow frequency based analysis Rainfall / runoff model based analysis Flood routings / event simulation Sample USACE guidance EM 1110-2-1417 - FLOOD-RUNOFF ANALYSIS EM 1110-2-1415 - HYDROLOGIC FREQUENCY ANALYSIS EM 1110-2-1413 - HYDROLOGIC ANALYSIS OF INTERIOR AREAS

USACE Hydrology for Kansas and Missouri Rivers Flow frequency based Kansas River – 2002 report (1920-1997) Missouri River – 2003 report (1898-1997) KS/MO river coincident peak – 2006 feasibility study Some historic peak stages available (e.g. 1844) Biggest effort: making the data sets consistent Dates reservoirs were closed, when they were filling Changes in consumptive uses

Hydraulic Study Options: Steady flow vs unsteady flow Fixed bed vs mobile bed Numerical models; 1, 2 or 3 dimensional Physical models Sample USACE Guidance EM 1110-2-1416 – RIVER HYDRAULICS EM 1110-2-1601 – HYDRAULIC DESIGN OF FLOOD CONTROL CHANNELS

1-d Hydraulic modeling

Example 2D model

Risk Based Analysis USACE requires uncertainty analysis for Flow frequency Stage / discharge Levee performance Stage vs damage functions EM 1110-2-1619 - RISK-BASED ANALYSIS FOR FLOOD DAMAGE REDUCTION STUDIES

FEMA Floodplain Info Focused on the flood with a 1% (1/100) annual chance of exceedance, but also map the 0.2% event (1/500)

Likely to be evolving… 30 Jan 2015 executive order

Missouri River Current Models Missouri River FEMA floodplain Based on 2003 USACE hydrology & profiles from unsteady flow model calibrated to 1993 FEMA Floodway model: Steady flow HEC-RAS model calibrated to 1% event USACE developed for FEMA, contact FEMA for the official version

Climate Change USACE guidance in ECB 2014-10 (expires May 2016) “USACE policy requires consideration of climate change in all current and future studies to reduce vulnerabilities and enhance the resilience of our water-resource infrastructure.” Changes other than climate threats that affect inland hydrology will continue to be evaluated in the manner described in current USACE guidance (e.g., Chapter 18, Evaluating Change in EM 1110-2-1417, Flood-Runoff Analysis; and EM 1110-2-1413, Hydrologic Analysis of Interior Areas).

Current Study Requirements A qualitative assessment of potential climate change threats and impacts potentially relevant to the particular USACE hydrologic analysis being performed. Doesn’t change the numbers, but can inform future without project conditions hydrology Future expansion to quantitative analyses is expected.

Example trend in Kansas, treated within hydrologic Uncertainty analysis already performed

Particular hydrology analysis Rainfall / runoff model study: extreme precipitation trends Ex: Upper Turkey Creek Feasibility Flow frequency: trends in peak stream flows and or reservoir inflow volume trends Ex: Kansas Cities Levees Phase II Ex: Manhattan, Kansas Feasibility Study

Resources NOAA regional climate change reports Climate models online (ecb gives a link)

Challenge answer

Three days later… May 11, 2007 ~ 225,000 cfs (KS River ~40,000 cfs) The Kansas River peaked at Desoto on May 8 at 120,000 cfs. In case asked, the 2011 flood peak was 32.6 ft at KC gage on the Missouri. May 11, 2007 ~ 225,000 cfs (KS River ~40,000 cfs)

Largest recorded flows: Kansas River Both pre dam: Kansas: 1951 flood – 510,000 cfs Missouri: 1952 flood – 397,000 cfs Kansas River at Bonner Springs or Desoto, Kansas Missouri River at St Joseph, Missouri

Hydraulic Engineer’s Answer: It depends… Generally the Missouri River but the Kansas River is capable of very large flows Post dam peaks: edge for Missouri River Missouri: 335kcfs (1993); 277kcfs (2011); 207kcfs (1987) Kansas: 170kcfs (1993); 146kcfs (1974); 121kcfs (1995) 0.2% (1/500 ACE) events about the same; but the Missouri produces big flows more often 200kcfs 1/50 ACE on KS vs 1/20 ACE on MO 150 kcfs 1/20 ACE on KS vs 1/5 ACE on MO